The main structure of a prior art speaker mainly comprise a vibration membrane which includes a sound diaphragm at an center section thereof, an annular surround edge and an annular supporting sheet. The annular surround edge is combined to an annular outer edge of the sound diaphragm and the annular supporting sheet is combined to an annular outer edge of the annular surround edge. A lower side of the vibration membrane is connected to a voice coil. A coil winds around the voice coil. The voice coil is wound with coils which is electrically conductive. A lower section of the voice coil is surrounded by a magnetic vibration element. A outer radius of the magnetic vibration element is smaller than an outer radius of the sound diaphragm. When the voice coil is conducted, it is interacted with the magnetic vibration element so that the voice coil is interacted with the magnetic vibration element. Therefore the voice coil will push the vibration membrane and thus air vibrates to emit sound. Variation of current to the coil will generate vibrations of different frequencies and thus to have different sound.
However, in the prior art speaker in the prior art, because the outer radius of the magnetic vibration element is smaller than the outer radius of the sound diaphragm, when larger sounds need, the speaker will operate in full power. However, this will induce the distortion of emit sound and moreover, sound quality cannot be retained. Furthermore, in the prior art since the magnetic vibration element in the speaker has a smaller size, the impact distance is short. This is unbeneficial to lower frequency sound to induce the sound quality in low frequency is worse.
Therefore it is desired to have a novel speaker which can improve the above mentioned defects in the prior art.